Calender roll for pressure treating materials



Oct. 10, 1967 E. KUSTERS ETAL 3,345,937

CALENDER ROLL FOR PRESSURE TREATING MATERIALS Filed April 26, 1966 2Sheets-Sheet 1 INYENTORS 00490 Kus revs BY Kuer Quoos E. KUSTERS ETALCALENDER ROLL FOR PRESSURE TREATING MATERIALS Filed April 26, 1966 Oct.10, 1967 2 Sheets-Sheet 2 INVENTORS BY 00490 Ku'srms Kum- Q0008 g flfrys United States Patent 3,345,937 CALENDER ROLL FOR PRESSURE TREATINGMATERIALS Eduard Kiisters, 457 Gladbacher Strasse, 415 Krefeld, Germany,and Kurt Quoos, Krefeld, Germany; said Quoos assignor to said KiistersFiled Apr. 26, 1966, Ser. No. 545,507

Claims priority, application Germany, Feb. 16, 1961, T 19,683 3 Claims.(Cl. 100155) ABSTRACT OF THE DISCLOSURE Technically, the disclosure is acalender having two rigid rolls or rollers between which is arranged asolid synthetic polyamide roller that is substantially solid throughoutits diameter excepting for possibly a small hole or bore extendingthroughout its axis and which does not interfere with its solidcharacteristics.

This is a continuation-in-part of application Ser. No. 314,439, filedOct. 4, 1963, and now abandoned, which was a continuation of applicationSer. No. 127,520, filed July 28, 1961, and now abandoned.

This invention relates to textile and paper calenders of the type usinga soft roll and at least one hard roll forming a nip through which thetextile or paper web passes to receive the calendering action.

In the prior art, a soft roll is made of stacked paper or cloth diskstightly compressed together with their edges finishedto form a truecylinder. The hard roll may be made of steel, for example, the hard andsoft rolls :are pressed toward each other under relatively high pressureand these rolls are usually intergeared and driven to obtain slippagebetween the hard roll and the web to promote the calendering action.

Such soft rolls are easily marked by the edges of the web and by splicesor other discontinuities 'in the webs surface.

When this occurs the surface of the roll must be refinished. Thisrequires removing the roll from the calender, machining, and returningthe roll to the calender. This disadvantage, among other disadvantages,has shown the need for improvement.

Press rolls of the type used on paper machines to dewater the wet paperweb have been covered tightly with a layer of elastically deformablerubber. The characteristics of rubber make it unsuitable for use as thesoft roll of a calender.

The physical and chemical characteristics of the synthetic polyamide orsuperpoly-amide materials suggest that such a material, having theproper degree of elasticity, when used instead of rubber should providea calender soft roll of improved non-marking characteristics whileproviding a satisfactory calendering action on the web. For example, thesuperpolyamide material known in the USA. as nylon, when used as acovering or sleeve shrunk on a rigid steel roll appears to be suitablefor use as a Calendar soft roll.

With the above in mind, calender soft rolls were made by shrinking asleeve of superpolyamide material, such as nylon, on a steel roll, butwhen such soft rolls were placed in normal service, working against theusual hard rolls, they rapidly destroyed themselves. The plasticcoverings became lumpy and loosened from the steel rolls.

Thus, the industry was presented with the problem that even though thesynthetic polyamide and superpolyamide materials appeared to be verysuitable for use as calender soft rolls, such materials cannot be usedin the normal 3,345,937 Patented Oct. 10, 1967 manner in a calenderoperating under commercial conditions.

One object of the present invention is to provide a calender soft rollusing effectively an appropriate synthetic polyamide or superpolyamidematerial, such as nylon, and which will be capable of operating with anadequately long service life when used commercially, working opposite ahard counter roll, to calender textile and paper Webs. Although intendedas a calender roll, such a roll might be used for other applicationsrequiring the operation of a soft roll forming a nip with a hard counterroll.

The present invention is based on thorough testing of plastic coveredrolls of various types, the term plastic" being used to mean appropriatetypes of synthetic polyamide and superpolyamide materials.

This testing showed that even a plastic of excellent physical qualityhas two troublesome properties, namely, poor heat conduction, and a veryhigh thermal expansion coeflicient. It was found that thesedisadvantages cannot be eliminated but must be compensated for by theroll construction.

To begin with, it was found fundamentally wrong to shrink a plasticcover on a steel shaft or roll for the following reasons:

Textile and paper webs are uneven throughout their length and cause anexcessive build-up of pressure in a localized area of the plastictightly covering the roll, which in turn causes local overheatingbecause the heat is not conducted away but builds up locally. When thisoccurs, even for a slight amount, a thick balloon-like bulb is formed bythe plastic which cannot move in an axial direction and equalize whenrestrained by the steel shaft or core. The result is excessive reversalsof bending in this localized area causing in turn higher pressurebetween it and the opposing hard counter roll, more heating, and

further enlargement of the plastic bulb. This effect continuesincreasingly and results in localized melting of the plastic coveringshrunk on the steel roll.

Further, the natural working of the soft roll plastic sleeve by itsbeing indented by the hard roll causes heat ing. Then the plasticexpands thermally and loosens from the steel shaft or core on which theplastic sleeve is shrunk. Without full support by the shaft or core theplastic sleeve receives more working until, again, it destroys itself.

According to the present invention the difficulties describedhereinabove are overcome or eliminated to a large extent by initiallycasting a solid cylindrical roll from a suitable polyamide orsuperpolyamide material, such as nylon in the U.S.A., and supportingthis roll on its side opposite to that forming the nip with the hardroll, by a a cylindrical roll preventing bending of this soft roll. In

other words, the plastic roll being solid throughout works between thehard roll with which the soft roll forms the nip, and a supporting rollwhich prevents bending of the plastic roll, in the direction of thelatters axis or longitudinally thereof.

. roll relative to its support roll. Because the solid plastic soft rollis running freely between the hard counter roll and the soft supportroll, the soft roll can expand and contract in all directions withoutintroducing problems other than for an adjustment of the nip pressure tokeep it constant, and this can be done automatically by known means.

Rolls constructed as described generally above when put in calenderingservice under commercial operating conditions have not only thenon-marking advantage expected of the plastic as an improvement overprior art soft rolls, but important additional advantages. For example,it was found that the elastic deformation and recovery of the plastic inthe nip formed by the plastic roll with the hard roll, exerts a slippingaction relative to the hard roll providing greatly improved calenderingeffects and in some respects previously unobtainable effects. Because ofthe slipping action, it is unnecessary to intergear the hard and softrolls as was usually necessary when using the prior art soft rolls.

Examples of the present invention are illustrated by the accompanyingdrawings in which:

FIG. 1 is an elevation of the solid plastic soft roll as it may beapplied to a textile calender.

FIG. 2 corresponds to FIG. 1 but shows a slight modification thereof andis a view that is partly in elevation and partly in longitudinal sectionto show its solid nature.

FIG. 3 somewhat schematically shows an end elevation of a textilecalender using the roll.

FIG. 4 corresponds to FIG. 3 but shows a different arrangement; and

FIG. 5 is an elevational view showing the solid roll used in a calenderwhich has been commercialized extensively.

In FIG. 1 the roll 1 is as described generally heretofore. It is a blockpolymerized, sometimes called mass, bulk or cast polymerized polyamideor superpolyamide material such as nylon. The material shall be of acharacter adapted to resist nip working pressures ranging from 350upwardly to 700 kg. per centimeter of length without being deformedappreciably to an elliptical shape due to the pressure exerted by acounter roll and the previously described supporting roll. A suitablematerial may have a modulus of elasticity ranging from 8,000-36,000kg./cm. To give an example of size, the diameter may be in theneighborhood of 200350 mm.

The roll 1a shown by FIG. 2 is a completely solid roll whereas the roll1 has a small diameter bore 1b formed through it to illustrate that Whenreference is made to a solid roll it should be understood thatsubstantial solidarity is meant. Any such bore 111 should be of verysmall diameter, as compared to the overall diameter of the roll 1 or 1a,to make the presence of the bore inconsequential. Preferably the roll ismade solid throughout.

The roll 1 is shown as having integral journals 2 and the roll 1a isshown as having corresponding journals 2a and, in addition, as havingbeen provided with annular series of notches or teeth 3 to permitengagement with the rotary driving element should any such arrangementever be wanted.

Instead of the integral journals 2 or 2a, rolls made according to thisinvention may have machined ends on which metal journals are mountedproviding the metal does not extend into the interior of the roll to anygreat extent.

In FIG. 3, the calender illustrated comprises end frame members 4, theroll 1 or 1a, and the previously mentioned and here illustratedsupporting roll 5. The calendering nip is formed with the roll 1 by ahard roll 6. The broken line indicates the web passing through the nipand being calendered, the roll 1 being offset, relative to the rolls 5and 6 in a direction opposite to the travelling direction of the web toassist in preventing deflection of the plastic roll in the webstravelling direction.

Another possible arrangement is shown by FIG. 4 wherein the roll 1 isvertically aligned with respect to the roll 6 and two rolls 5a are usedto support the roll 1 at two locations.

In the commercial form shown by FIG. 5, the rolls are numbered tocorrespond with the foregoing, the arrangement here being like thatshown in FIG. 3. The support roll 5 is journaled by bearings 7 mountedby brackets 8 sliding in guideways 9 formed by the frame members 4a. Thenip pressure is applied by pushing upwardly on the support roll 5 by theuse of pressure applying elements 10. Thus the roll 5 pushes the plasticroll 1 upwardly and applies the nip pressure required between this roll1 and the hard roll 6. The latter is journaled by bearings 11 mountedrigidly with respect to the frame members 4a, and the plastic roll 1 hasits journals mounted by antifriction bearings 12 supported by the framemembers 411 through swinging arms 13. In other words, the journals 2 arereally roll necks which are mounted by the inner races of conventionalroller anti-friction bearings.

The hard roll 6 is ordinarily made of steel with either a smooth workingsurface or one that is engraved or otherwise forrned as required forcertain effects of calendering. This upper or hard roll 6 is driven by amotor 14 through a drive indicated at 15.

This is a textile calender and the travel of the textile web will be asindicated in FIG. 3. In this commercial form, the roll 1 is offset asshown by FIG. 3.

Many textile calendering operations require that the roll 6 be heated,the passages 6a in FIG. 3 indicating suitable heating means. The heat ofthis is transmitted to the roll 1 and when properly controlled may givethe roll 1 a desirable degree of slightly softer elasticity. Should theheat transfer be excessive so as to unduly soften the roll 1, this heatmay be more or less removed by providing the roll 5 with cooling means,generally indicated in FIG. 3 by the passages 5a.

The support roll 5 should apply uniform supporting pressure to the softroll 1, at its side opposite the hard roll 6, which is substantiallyuniform throughout the length of the soft roll 1 which forms the workingnip with respect to the hard roll 6. This may be effected by making theroll 5 a controlled deflection roll or controlled crown roll. An exampleof such a roll is the well-known roll sold under the trademark SwimmingRoll by Eduard Kt'isters Maschinenfabrik of Germany. The construction ofsuch a roll is shown by the Appenzeller Patent 2,908,964 issued toValentin Appenzeller on Oct. 20, 1959. This particular kind of rollcontrols the roll deflection by hydraulic liquid working under pressuredirectly on the inside of a shell which forms the rolls outer element.Therefore, by controlling the temperature of this liquid, the coolingaction exerted on the plastic roll 1 may be controlled. The liquid flowsto and from such a roll so it may be cooled.

The offsetting of the roll 1 illustrated by FIG. 3, prevents bending ordeflection of the roll 1 cross-wise as previously indicated.

In operation, with the motor 14 driving the roll 6, the web passesbetween this roll and the roll 1 through the nip formed by these tworolls. The controlled deflection roll 5 provides the roll 1 with uniformpressure support throughout the active length of the roll 1. If the roll1 is relatively short the roll 5 need not be a controlled deflectionroll but may be a plain roll because it will be sufficiently short toavoid appreciable beam flexure. The roll 6 is ordinarily heated.

The roll 1 is elastically indented by the roll 6 so as to provide thesuperior calendering previously noted. In turn, being a plasticmaterial, the roll 1 is heated by the elastic deformation it receivesthroughout the zone of the nip it forms with the roll 6. This, possiblyplus heat transferred from the roll 6, heats at least the surface of theroll 1, with this heat to some degree penetrating throughout thediameter of the roll 1.

As a result of the above, the roll 1 begins to expand. However, becausethe roll 1 is solid, excepting possibly for a bore hole of a diameterinsuflicient to materially effect its solidarity, it can expand freelyin a radial direction. Because its ends are free to expand in an axialdirection there is nothing to restrict thermal growth in that direction.As the diameter of the roll 1 increases the pressure applied by thedevices 10 may be controlled to keep the nip pressure uniform betweenthe rolls 1 and 6.

The roll 1 is free to thermally expand and contract without interferenceby anything. Any tendency for 10- calized expansion to occur does notresult in destruction of the roll 1 because the plastic is free to moveas re quired for equalization.

Calenders of the kind illustrated by FIG. 5 have now been in successfuloperation under commercial conditions for relatively long periods oftime. Plastics such as nylon do not tend to recover elastically to theirfullest extent immediately. The operating speed of a machine using thesoft roll of the present invention should not be so excessive as toexclude the possibility for plastic leaving the nip between the rolls 1and 6 to elastically recover substantially completely before it iscontacted by the support roll 5. Because the support roll 5 is cooled,elastic recovery of the plastic in contact with this roll and afterleaving this roll is relatively quick.

It can be seen from the foregoing that the present invention teaches forthe first time that a calender roll may be made of a plastic materialsuch as nylon, having the tendency to heat and thermally expand to arelatively great degree when repeatedly deformed by contact with thenecessary calendering hard roll, providing the plastic roll is in a formfree to thermally expand and contract without substantial restraint, inall directions. In the present instance an example of this principle isa plastic roll that is completely solid, or substantially so for allpractical purposes, and which is mounted between two metal rolls, onesupporting the plastic roll and the other forming a calendering nip.

Essentially, the principle is that to provide the cylindrical plasticrolling surface the plastic body mustbe solid andsupported uniformlythroughout its length on one side with its other side forming, with acalendering roll, the nip.

It is to be understood that the plastic body should in no instance be sothin as to provide insuifi-cient plastic between the two hard metalrolling surfaces as to permit the elastic deformation by the two rollingsurfaces to extend through the plastic body in its radial direction. Aplastic roll member of any reasonable dimensions avoids this effect.

What is claimed is:

'1. A calender for webs of paper or textile material comprising apolyamide roller and at least two substantially rigid rollerssubstantially on opposite sides of said polyamide roller, said polyamideroller consisting entirely of solid synthetic polyamide materialthroughout substantially the entire diameter of the roller and beingfree of a supporting shaft at the core, said polyamide roller having adiameter of at least 200 mm. and a modulus of elasticity of 8,000 to36,000 kg./cm. at room temperature whereby deformation of the polyamideroller at the core at calendering pressure is avoided.

2. The calender of claim 1 in which at least one of said rigid rollerscomprises a controlled deflection roll applying supporting pressure tosaid polyamide roller with substantially uniform pressure throughout itslength.

3. The calender of claim 1 having means for cooling the surface of atleast one of said rigid rollers.

References Cited UNITED STATES PATENTS 94,802 8/ 1869 Cramer 68-244 T737,571 9/1903 Bray.

2,763,893 9/1956 Hall 264-293 2,851,869 9/1958 Quoos et a1. -170 X2,908,964 10/ 1959 Appenzeller 29-110 3,222,209 12/1965 Brundige et a129-132 X LOUIS O. MAASSEL, Primary Examiner.

1. A CALENDER FOR WEBS OF PAPER OR TEXTILE MATERIAL COMPRISING APOLYAMIDE ROLLER AND AT LEAST TWO SUBSTANTIALLY RIGID ROLLERSSUBSTANTIALLY ON OPPOSITE SIDES OF SAID POLYAMIDE ROLLER, SAID POLYAMIDEROLLER CONSISTING ENTIRELY OF SOLID SYNTHETIC POLYAMIDE MATERIALTHROUGHOUT SUBSTANTIALLY THE ENTIRE DIAMETER OF THE ROLLER AND BEINGFREE OF